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Fp4nc Z-axis Slideway Adjustment

Rider-83

Aluminum
Joined
Nov 20, 2005
Location
England
Is there a procedure to remove any wear in the z-axis ? My table 'leans' forward approx 0.1mm and requires shimming each time I fit it. Are there any 'gibs' to adjust ?
 
There are two adjustments on the vertical slide to compensate for wear.

There is a tapered gib that controls the slide "rock" from side to side. This gib adjusts the space of the slide between the box ways, and it is on the operators side of the inside of the boxes. You remove or grind the shims under the holding strap connected to the gib. This allows the gib to move up and makes it tighter. Before making this adjustment you should check the wear on the machine. Use a good tenths reading indicator and position it so that you can read the top outside edge of the vertical casting (not the table). Position the slide at the top of the vertical travel and run the table full right set the indicator to zero and move the table full left. Note the indicator movement. Move the table down on the vertical and repeat the test.
Do this in at least 3 places along the vertical ways...try to do one test where you normally use the machine most. You will likely get the lowest reading at full down and full up. Adjust the gib to get something around .12-.15 mm total movement max. Of course if trhe box ways are worn you will get more where it is worn. Like any machine you can't over tighten the gib to compensate for a worn spot if it makes the non worn points too tight!

As to wear that makes the table lean down at the front edge, this is a natural progression of the Deckel design.
There are two issues. If the out of square is significant the ways in the sliding casting have almost surly become worn. They tend to wear in a barrel shape staying relatively unworn in the center and most worn at trhe bottom. The cure here is to scrape the worn surface flat again. If large amounts are required to accomplish this then a fitting or Moglice or Turcite to bring everyuthing back to standars height will be required.
The clearance of the vertical slide in the front/rear direction is controlled by the plate gibs bolted to the rear of the slide. These (on the FP-NC's) are fitted with Turcite where they touch the box ways, and steel where they fit up to the slide face. The only way to adjust these is by grinding or scraping.
The drill goes like this....
Setup the plate on a surface grinder with the outside up. Check to be sure trhe plate is flat and the grinder is not goint to pull the plate flat by the magnetic chuck Any "pull down" here will translate into a curved and non flat way surface when you are done.
Grind the back side of both plate gibs, just to clean up.
Turn over and grind the inside surface to male the Turcite flat and remove any wear ridges. ...grind only the turcite. Zero the depth dial on the grinder.
Carefully measure the height between the back surface of the box way and the mounting face of the vertical slide. Check in several places and be sure you have the slide pulled up to the box way with some clamps and wood to protect the sliding surfaces. You are looking for the lowest number. (as the slide wears the value here will get larger)

The measured value between the box way and gib mounting face of the vertical slide is the value you need between the Turcite on the plate and its mounting face. Finish the plate gib by grinding the steel mounting face to get the measured value plus clearance. Somewhere around .001-.0015" of clearance is fine if the box ways are not too worn...allow more if thinfgs are not so good.

Be aware that if the position of the vertical slide is changed any amount (scrapingf it to correct wear) the position of the "Z" axis ball screw will change relative to the base mounting and cause it to run at an angle...this is not good.
The screw position can be adjusted by "floating" it with the vertical slide as far down as possible , blocking the slide , removing the servo belt, loosing the retaining bolts to allow the screw to move where it wants, then re tighten the bolts and finally, ream the dowel holes and fit OS dowels......

Cheers Ross
 
Of course the easy solution would be to scrape your table mounting face to make it so it was flat when mounted...Actually i believe the factory setup has the tables point slightly up at the outside edge when mounted to allow for the sag when parts and vise are mounted.
Cheers Ross
 
position it so that you can read the top outside edge of the vertical casting (not the table)

Hi Ross, I'm not following you here. By vertical casting do you mean the top of the column? Any chance you could post a picture of the setup?

-Dave
 
My FP2NC'S table droops downward about 0.002" in 12". Mostly I don't worry about it. If I really care for some specific part, I machine soft jaws in the vise mounted sideways, or machine a temporary bed plate. If you machine the workpiece mounting points in-situ, they should be as as well aligned as the machine can provide. I'd love to have an adjustable table to tweak out this minor tilt, but it's not a high priority.
 
Hi Ross, I'm not following you here. By vertical casting do you mean the top of the column? Any chance you could post a picture of the setup?

-Dave
Dave:
By vertical casting or slide i am talking about the part of the machine that would be called the "Knee" on a Bridgeport....this is the casting that slides up and down on the machine to provide the "Z" travel and it also is one side of the ways for the table to provide "X" travel. In effect it is the joint between the table and the machine column.
It provides the sliding surfaces for two (2) of the machines 3 axis movements.
Cheers Ross
 
Dave:
Actually my example is really not correct! The vertical slide on a Deckel is the same as a part on a Bridgeport that goes between the Knee and table and is generally known in the US machine tool world as the Saddle.
This is the piece that fits between the table (on a BP) and the top of the knee. It is the part that combines or allows two axis movements.
In the Deckel's case the saddle is turned 90 degrees and instead of making up to the top of the knee it mounts to the face of the column on the vertical ways.

Cheers Ross
 
For a couple of years now I have been asking myself, why is this Deckel (fp1) so much more accurate than a Bridgeport or even the Hardinge mill that I spent a month hand-scraping? When I used the machines, the results spoke for themselves, even though the fp1 was made in the 50's and was original in the sense that none of the running gear had been replaced or rebuilt.

Ross, after reading your comments above it started me thinking, the reason for the improved accuracy is that the table in a Deckel-style mill has only two degrees of freedom in relation to the column (X&Z), while a knee mill has all three, so any slop of table position on a Deckel will be better than an equivalent condition knee mill.

-Dave
 
I measured the rock of the table sideways, i moved the table from end to end and did this in 80mm steps in Z axis.

I had 0.001mm dial indicator like in the picture. Is this Correct way, or am i way off with my method?

I didnt find any picture of used method and didnt fully understand from writings.

Top was 0.01mm and ~ 0.014 - 0.016mm anywhere else, these are total amount what indicator moved from end to end.

IMG_20201203_173250.jpg
 
Harri:
Your method will work, but it is not going to give you as accurate a reading as the method i suggested above.
Not where i can snap a photo just now so i will try to describe the setup a little better.

The problem with your setup is that the reading point is too narrow , or more correctly too close to the center of movement so what you get for a reading will show smaller than it is in reality.

You are looking to measure the amount of "rock" or tip that happens when the "X" slide moves from max X minus to max X plus.
The "Rock" happens as a result of clearance between the vertical slide (the casting that moves up and down on the vertical ways (Z)).

To gauge the amount of actual movement , place your magnetic base on the large flat face of one of the box ways just above the top of the vertical slide
Extend the arm of your magnetic base to the side running horizontal, more or less parallel to the "X" axis,

Locate your indicator finger at the farthest end of the vertical slide at its top ...You are now taking your readings at a point furthest from the Z ways on top of your vertical slide...

Result :making your reading further from the contact of the Z box ways means larger movement...Think of it as a door...at the hinge , measuring the opening move, the reading is fairly small.. The same opening measured at the edge of the door away from the hinge will show a much greater amount of movement......

Cheers Ross
 
Thank you Ross, what would be the minimum acceptable movement when gib is adjusted?

You wrote above
"Adjust the gib to get something around .12-.15 mm total movement max"

This sounds quite a lot?
 
Those were values given to me by a professional Deckel service engineer.....
Remember that those numbers represent the total movement/total runout.....running the "X" slide max travel each direction....
Values are relevant to the FP4NC. Smaller machines likely would have proportionally smaller figures
Cheers Ross
 
Last edited:
Okay, thank you for your help. I'll need to try your method and see what kind of movement im getting.
 
I did like you have told, i still get only ~ 0.01mm - 0.012mm movement. Did this on multiple spots.

Then i did whats in the attached picture.
I had A 1000mm straight edge Din 874/1 which is straight within 0.021mm/1000mm.

I zeroed to middle and i get ~0.015mm movemet on both ends.


IMG_20210224_182321.jpg
 
At top of the z axis ways, there is this colorization. Looks like they are hardened?

IMG_20210301_190538.jpg
 
Movement seems very good...especially if its consistent over the total vertical.
Do a sample scrape at the very bottom of one of the box faces....If its hardened the scraper will skate....
Grinding is the only option on the hardened way machines...been there tried that.
Cheers Ross
 
There's discussion of "scraping" Prototrak bed mills with a hand grinder in the scraping forum here, That would probably be a solution for the hard Deckel ways too.
 
Y axis moves within 0.01mm full travel. The table leans down at front about 0.04mm. Y axis fully extended, i can see some needle movement if i pull down, but on its own weight it moves suprisingly straight.

Seems odd that the table is so much off at y axis direction.
 








 
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